using System;
using MultiWheelC.TrajectoryPlanning.CoarsePath;
using MultiWheelC.TrajectoryPlanning.EMPlanner;

namespace EMPlannerVerificationHost;

internal static class ExecutorChecks
{
    public static void Run()
    {
        VerifiesGearSwitchSequence(TravelDirection.Forward, TravelDirection.Reverse, "forward-to-reverse");
        VerifiesGearSwitchSequence(TravelDirection.Reverse, TravelDirection.Forward, "reverse-to-forward");
        VerifiesExecutorSamplesBoundariesAndCompletesAtSafeTerminals();
    }

    private static void VerifiesGearSwitchSequence(TravelDirection currentDirection, TravelDirection desiredDirection,
        string name)
    {
        var machine = new GearSwitchStateMachine(0.01d, 0.20d);
        DateTimeOffset start = DateTimeOffset.UnixEpoch.AddSeconds(500d);

        GearSwitchStateUpdate approaching = machine.Update(start, 0.10d, desiredDirection, currentDirection, false, false,
            false);
        Verification.Equal(GearSwitchState.ApproachingGearSwitch, approaching.State, name + " approaches switch");
        Verification.True(approaching.AllowsTrajectoryMotion, name + " approach permits trajectory motion");

        GearSwitchStateUpdate holding = machine.Update(start.AddMilliseconds(100), 0.005d, desiredDirection,
            currentDirection, false, true, false);
        AssertHeld(holding, GearSwitchState.HoldingZero, name + " holds at boundary");

        GearSwitchStateUpdate movingAgain = machine.Update(start.AddMilliseconds(110), 0.01d, desiredDirection,
            currentDirection, false, true, false);
        AssertHeld(movingAgain, GearSwitchState.HoldingZero, name + " holds while measured speed is at tolerance");

        GearSwitchStateUpdate dwellRestart = machine.Update(start.AddMilliseconds(120), 0d, desiredDirection,
            currentDirection, false, true, false);
        AssertHeld(dwellRestart, GearSwitchState.HoldingZero, name + " starts zero-speed dwell");
        GearSwitchStateUpdate dwellShort = machine.Update(start.AddMilliseconds(319), 0d, desiredDirection,
            currentDirection, false, true, false);
        AssertHeld(dwellShort, GearSwitchState.HoldingZero, name + " does not request before full dwell");

        GearSwitchStateUpdate requesting = machine.Update(start.AddMilliseconds(320), 0d, desiredDirection,
            currentDirection, false, true, false);
        AssertHeld(requesting, GearSwitchState.RequestingDirectionChange, name + " requests after continuous dwell");
        Verification.True(requesting.RequestDirectionChange, name + " emits exactly one direction request");

        GearSwitchStateUpdate awaiting = machine.Update(start.AddMilliseconds(321), 0d, desiredDirection,
            currentDirection, false, true, false);
        AssertHeld(awaiting, GearSwitchState.AwaitingDirectionConfirmation, name + " awaits confirmation");
        Verification.True(!awaiting.RequestDirectionChange, name + " does not repeat direction request");

        GearSwitchStateUpdate following = machine.Update(start.AddMilliseconds(322), 0d, desiredDirection,
            desiredDirection, true, false, false);
        Verification.Equal(GearSwitchState.Following, following.State, name + " follows confirmed next segment");
        Verification.True(!following.HoldZero && following.AllowsTrajectoryMotion,
            name + " resumes only after confirmation");

        GearSwitchStateUpdate completed = machine.Update(start.AddMilliseconds(323), 0d, desiredDirection,
            desiredDirection, false, false, true);
        AssertHeld(completed, GearSwitchState.Completed, name + " completes at terminal while holding zero");
        Verification.True(completed.IsTrajectoryComplete, name + " marks terminal completion");
    }

    private static void VerifiesExecutorSamplesBoundariesAndCompletesAtSafeTerminals()
    {
        DateTimeOffset effectiveAt = DateTimeOffset.UnixEpoch.AddSeconds(600d);
        var executor = new TrajectoryExecutor();
        EmTrajectory gearTrajectory = CreateTrajectory(effectiveAt, TravelDirection.Forward,
            EmBoundaryType.GearSwitchApproach, EmTerminalType.GearSwitch);

        TrajectoryExecutionState approaching = executor.Update(effectiveAt.AddSeconds(0.10d),
            CreateMeasuredState(0.10d, effectiveAt.AddSeconds(0.10d), 60L), gearTrajectory, TravelDirection.Reverse,
            TravelDirection.Forward, false);
        Verification.Equal(GearSwitchState.ApproachingGearSwitch, approaching.GearSwitchState,
            "executor enters approach before exact gear boundary");
        Verification.NearlyEqual(0.10d, approaching.SelectedPoint.SignedLongitudinalVelocity,
            "executor samples moving approach point");

        TrajectoryExecutionState holding = executor.Update(effectiveAt.AddSeconds(0.30d),
            CreateMeasuredState(0.005d, effectiveAt.AddSeconds(0.30d), 61L), gearTrajectory, TravelDirection.Reverse,
            TravelDirection.Forward, false);
        AssertHeld(holding, GearSwitchState.HoldingZero, "executor holds at exact gear boundary");
        Verification.Equal(EmBoundaryType.GearSwitchApproach, holding.SelectedPoint.BoundaryType,
            "executor preserves exact gear boundary point");
        Verification.NearlyEqual(0d, holding.SelectedPoint.SignedLongitudinalVelocity,
            "executor does not release nonzero speed while holding");

        foreach (EmBoundaryType terminalBoundary in new[] { EmBoundaryType.Goal, EmBoundaryType.RollingSafetyStop })
        {
            var terminalExecutor = new TrajectoryExecutor();
            EmTrajectory terminal = CreateTrajectory(effectiveAt, TravelDirection.Forward, terminalBoundary,
                terminalBoundary == EmBoundaryType.Goal ? EmTerminalType.Goal : EmTerminalType.RollingSafetyStop);
            TrajectoryExecutionState completed = terminalExecutor.Update(effectiveAt.AddSeconds(0.30d),
                CreateMeasuredState(0d, effectiveAt.AddSeconds(0.30d), 62L), terminal, TravelDirection.Forward,
                TravelDirection.Forward, false);
            AssertHeld(completed, GearSwitchState.Completed, "executor completes " + terminalBoundary);
            Verification.True(completed.IsTrajectoryComplete, "executor marks " + terminalBoundary + " completion");
        }
    }

    private static void AssertHeld(GearSwitchStateUpdate update, GearSwitchState expectedState, string name)
    {
        Verification.Equal(expectedState, update.State, name + " state");
        Verification.True(update.HoldZero && !update.AllowsTrajectoryMotion, name + " forbids nonzero motion output");
    }

    private static void AssertHeld(TrajectoryExecutionState state, GearSwitchState expectedState, string name)
    {
        Verification.Equal(expectedState, state.GearSwitchState, name + " state");
        Verification.True(state.HoldZero && !state.AllowsTrajectoryMotion, name + " forbids nonzero motion output");
    }

    private static VehicleMotionState CreateMeasuredState(double speed, DateTimeOffset capturedAt, long sequenceId)
    {
        return new VehicleMotionState(new Pose2D(0d, 0d, 0d), speed, 0d, capturedAt, sequenceId);
    }

    private static EmTrajectory CreateTrajectory(DateTimeOffset effectiveAt, TravelDirection direction,
        EmBoundaryType terminalBoundary, EmTerminalType terminalType)
    {
        double signedSpeed = direction == TravelDirection.Forward ? 0.10d : -0.10d;
        var metadata = new EmTrajectoryMetadata("executor-" + terminalBoundary, effectiveAt, effectiveAt, 70L,
            "executor-reference", 60L, string.Empty, 4, direction, terminalType);
        return new EmTrajectory(metadata, new[]
        {
            new EmTrajectoryPoint(0d, 0d, 0d, signedSpeed, 0d, 0d, 4, 0d, 0d, direction, EmBoundaryType.None, 0d, 0d),
            new EmTrajectoryPoint(signedSpeed * 3d, 0d, 0d, 0d, 0.30d, 0d, 4, 0.03d, 0.03d, direction,
                terminalBoundary, 0d, 0d),
        });
    }
}